Harry w



Mar. 27, 1923. 1,449,751

H. W. HARDINGE ROD MILL Filed Nov. '7, 1921 Ez' .2 F1 4 bl NvENTOR 37 T m/w ATTORNEY 5 Patented Mar. 27, 1923.

UNITED STATES HARRY W. HARDINGE, OF NEW YORK, N. Y.

ROD MILL.

Application filed November 7, 1921. Serial No. 513,221.

To all whom it may concern:

Be it known that I, HARRY V. HARDINGE, a citizen of the United States of America, residing at New York, in the county and State of New York, have invented certain new and useful Improvements in Rod Mills, of which the following is a full, clear, and exact description.

This invention relates to grinding mills. More particularly it relates to rod mills and has for one of its more important objects to reduce the wear on the ends walls of such mills.

Another object is to provide a cylindrical rod mill in which the wear on the cylinder ends of the mill is reduced to a minimum without materially increasing the wear on the rods.

A further object is to provide a combined cylindrical and conical mill embodying the invention. Other objects and advantages will appear as the invention is hereinafter disclosed.

Referring to the drawings which illustrate what I now consider preferred forms of the invention:

Figure 1 is a somewhat diagrammatic longitudinal section of a mill embodying the invention.

Figs. 2, 3 and 4: are end views of some of the various forms of rods which may be employed.

Fig. 5 is a view similar to Fig. 1 but illustrating a combined cylindrical and conical mill.

In order to facilitate disclosure of the present invention I shall briefly explain the construction and operation of a type of cylindrical rod mill heretofore proposed. Such a mill comprises a cylindrical body portion rotatable about its cylindrical axis with the latter in a horizontal position. The ends of such a mill are substantially plane and perpendicular to the rotational axis, each end being provided with a hollow trunnion. One of these trunnions constitutes an inlet for the material to be disintegrated and the other an outlet for the discharge of the material from the drum. A plurality of cylindrical or other rods each of substantially uniform cross-section throughout its length are mounted for free rolling movement inside the drum, In the operation of such a mill any rod assuming an uppermost position rolls down over the pile of rods below, the direction of travel being such that the successive positionsoccupied by the axis of each rod are parallel to each other and to the axis of the drum. Due to this rolling movement of the rods, and the impact on reaching the bottom, material is disintegrated. Such a mill possesses an advantage over other types of rod mills in that the substantially pure rolling action of the rods is conducive to comparatively long life of the rods. should slide with relation to each other the useful life of the rods would be greatly reduced. However, it has been found in practice that the wear upon the end plates of the drum due tothe contact therewith of the ends of the rods is excessive and too frequent renewals are necessitated. I

thers have attempted to meet this problem by leaving one end of the drum entirely open and so inclining the axis of the drum,

If the rods the drum-contained or tapering the drum, or both, or adopting expedients to cause every rolling rod to roll towards the closed end of the drum at all times in the operation, as to prevent the rods from dropping or sliding out of the drum. But such expedients form no satisfactory solution because at best the problem is only half met thereby. Tilting the axis of the drum, or tapering the drum, or causing the rods to roll toward the closed end, increases the wear on the closed end of the drum, due to the increased end thrust of the rods, which, obviously, reduces the end-platewear but little. Moreover, any expedient or means which causes the rods to slide with respect to each other and over one another, thereby seriously reduces the life of the rods.

Well knowing that others had met with indifferent and unsatisfactory results in attempting to solve the problem of reducing end plate wear without materially reducing the life of the rods it occurred to me that any real solution would involve reducing such wear at one, or preferably each, end of the drum without increasing it at the other and decreasing the life of the rods.

If both ends of the cylinder might be entirely omitted there could be no wear of end plates. But then there would be nothing to prevent the rods from slipping or sliding out of the mill, nothing to prevent the escape of material before it had been reduced to fines of the desired size, and the advantage of comparatively small hollow trunnions if these are desired would be lost. It then occurred to me that, instead of employing plane ends, oppositely and outwardly directed ends of diminishing crosssection, preferably conical, might be employed. But my long experience with conical mills and mills having conical portions and my familiarity with their action gave me little hope that the sought-for solution would be found in that direction. In fact, one would suppose that such conical ends would cause the rods to become tangled and twisted in the conical ends and their desired free rolling action seriously interferred with. However, by actual construction, and test of a device such as that shown in Fig. 1, I discovered that I had satisfactorily solved the problem of reducing end wear.

Referring to Fig. 1 it will be seen that the mill there illustrated comprises a drum having a cylindrical body portion 10, conical end portions 11, 12, each of the latter terminating in a hollow trunnion, 13 and 14. respectively. Stationary bearings 15 and 16, surrounding the trunnions 13 and 14, serve to support the drum for rotation about the horizontal axis X X which is also the axis of the cylindrical body portion 10. Means, comprising a spur gear 17 are provided for rotating the drum about its axis X X. A plurality of rods 18, preferably clyindrical rods, are provided within the drum. If desirable the drum may be provided with a hand-hole or manhole, and cover plate 19.

therefor, to facilitate insertion and removal of rods into and from the drum. It will be noted that each of the rods 18 is not only greater in length than the diameter of the cylindrical body portion 10 but also of substantially the same length as said body portion.

In operation, materialto be ground is fed through the trunnion 18 into the, rotating drum where it is subjected tothe rolling and impact action of the rods 18. The fines leave the mill through the outlet trunnion 14. Due to the provision of the conical ends 11, 12, the rods, 18 are constrained to move so that the successive positions of the axis of each rod are parallel to each other and to the axis X-X. If any rod 18 slides beyond the ends of the body portion 10 it is quickly restored to the relative position shown in the Fig. 1 by one or the other of the conical ends 11 and 12. So effective is the operation. of the conical ends that when the rods 18 were deliberately displaced to a great degree beyond the ends of the body portion 10, they were quickly restored to normal, desired position within said body portion upon rotation of the drum. The wear 011 the end plates is practically eliminated. The motion of the rods is substantially a pure rolling motion so that their useful life is long. By virtue of the conical inlet end 11, the material to be ground is permitted quickly to enter the interstices between rods 18 and quickly to be discharged by virtue of the conical outlet 12. By constructing the conical end 12 in suitable form (well known to those familiar with my conical mills and my prior patents relating to the same) the said end 12 will not only accomplish the above-mentioned functions but will serve also as a means for automatically assorting the material according to size.

lVhile the rods 18 are preferably cylindrical as shown in Figs. 1 and 2, they may in certain cases assume the form of hexagonal prisms, as shown in Fig. 8 at 18 or square prisms as shown in Fig. l at 18", or other forms in which the crosssection of each rod is uniform (i. e., non-tapering throughout the length of the rod).

Cylindrical rod mills are limited in their lield of utility by the fact that they cannotbe satisfactorily employed except for comparatively coarse work. In Fig. 5 I show a form of machine which embodies the invention shown in Fig. 1 and also a conical mill in which the discharge of the cylindrical mill is reduced further to particles of the desired degree of fineness. In this form, of mill the parts 10, 11, 18, 15, 17,

18 and 19 will at once be recognized in of the cylinder 10 and is provided with an opening 21 preferably of the same size and in line with the openings in the trunnions 13 and 1 F. The conical end 12 hollow trunnion 14B and stationary bearing 16 and balls or other suitable grinding media 22 complete the conical mill shown to the right of the wall 20.

The operation and advantages of the instrumentalities including the wall 20 and elements shown to the left thereof in Fig. 5, are substantially the .same as that. set forth in connection with Fig. 1 and therefore need not be set forth in detail. Material fed through trunnion 18 is reduced to particles of a predetermined size in the body portion 10 by the rods 18. The ground material then passes through the opening 21 into the conical mill where the particles are further reduced in size by the now well known conical mill action.

It will be understood that I have omitted illustration of such well known expedients as linings, feed chutes, etc, these may be provided and modifications resorted to without departing from the scope of the inven tion as defined in the appendedclaims.

What I claim is l. A grinding mill comprising in combination, a rotatable drum having a substantially cylindrical body portion, an outwardly-extending conical inlet portion secured at its base to one end of said body portion, an outwardly-extending conical outlet portion secured to the other end of said body portion for automatically classifying material according to size, an intermediate cone-shaped wall in said drum and extending in an opposite direction with respect to said first named conical inlet portion, a plurality of freely rolling rods mounted within said drum between said conical inlet portion and intermediate wall, each of said rods being of greater length than the greatest interior diameter of said body portion and of substantially uniform cross section throughout its length, and a plurality of freely tumbling elements within said conical outlet portion and in said body portion between the latter and said intermediate wall.

2 A grinding mill comprising in combination, a rotatable drum having a substantially cylindrical body portion and an inlet opening, an outwardly-extending substantially conical member secured at its base to one end of said body portion, an outwardlyextending substantially conical outlet member secured to the other end of said body portion, and a plurality of freely rolling rods mounted within said drum between said substantially conical members, each of said rods being of substantially the same length as said cylindrical body portion and of substantially uniform throughout its length.

3. A grinding mill comprising in combination, a rotatable drum having a substantially cylindrical imperforate body portion and an inlet opening, an outwardly-extending substantially cone-shaped member secured at its base to one end of said body portion, an outwardly-extending substantially cone-shaped outlet member secured to the other end of said body portion, and a plurality of freely rolling rods mounted within said drum between said conical members, each of said rods being of substantially the same length as said cylindrical body portion and of substantially uniform cross-section throughout its length.

4. A grinding mill comprising in combination, a rotatable drum having a substantially cylindrical body portion, an outwardly-extending substantially conical inlet member secured at its base to one end of said body portion, an outwardly-extending substantially conical outlet member secured to the other end of said body portion, and a plurality of freely rolling rods mounted within said drum between said substantially conical members, each of said rods being of substantially the same length as said cylindrical body portion and of substantially uniform cross-section throughout its length.

In testimony whereof I hereto aflix my signature.

cross-section HARRY WJHARDINGE. 

